Bag for bulk material

ABSTRACT

A bag for bulk material made of paper and/or other sheet material, having at least one bottom formed in a cross bottom or block bottom folding manner, the bottom fold having two side flaps which are folded about side fold lines extending in the longitudinal direction of the bottom to form the bottom, the side flaps forming an overlap in the closed state, the width of the overlap being a maximum of 10 millimeters, preferably a maximum of 6 millimeters and further preferably a maximum of 4 millimeters.

BACKGROUND OF THE INVENTION

The invention relates to a bag for bulk materials such as cement, granules or other powdered or fine-grained building materials, chemicals or foodstuffs having at least one cross or block bottom.

Such bags are typically formed from a flat or web-like material, preferably paper and/or plastic. They are used in particular for the packaging and distribution of powdered or fine-grained bulk materials. Common sizes are 5 kg, 10 kg and 25 kg.

For the production of such bags, single- or multi-layer webs of flat material, e.g. paper and/or film webs, are formed in a so-called tuber into an endless tube and singulated into tube pieces of suitable length, from which the bag is finally formed, e.g. by means of a cross or block bottom folding. Towards the end of the bag making process, the bottom folding is usually fixed by suitable bonding. For this purpose, the side flaps of the bottom fold are often closed one after the other and glued together in the area of a comparatively wide overlap.

On the one hand, so-called open cross-bottom or block-bottom bags are known, which have a cross-bottom or block-bottom as a fixed bottom and are open at the top for filling the bag and are only closed, e.g. sewn and/or glued shut, after filling. Also known are so-called valve bags with two opposing cross or block bottoms, one of which is designed as a fixed bottom and the other as an opposing valve bottom into which a valve tube is inserted for filling the bag and which is closed after filling, e.g. by welding.

FIG. 1 shows the feeding of a cross bottom according to the prior art. In the afore-mentioned cross or block bottom folding process, the side flaps are typically folded shut last, one after the other. In the closed state, the two side flaps usually have a comparatively wide overlap, in the area of which a glue is located to fix the bottom fold.

A sufficiently wide overlap is required for mutual bonding of the side flaps. In the case of previously known bags, the width of the overlap ranges up to 2.5-5 centimeters. This requires sufficiently wide side flaps, which is associated with a corresponding material expense. Since the generic bags are produced and sold in large quantities, even minor material savings can lead to relevant cost advantages. Also known are bags in which a gap remains between the closed side flaps so that the closed side flaps do not overlap. However, in the case of bags of this type, adequate protection of the filling contents in the bottom area is often not ensured, especially in the case of multilayer bags with a film or barrier layer. In addition, the bottom of the bag is less stable in the area of the gap.

SUMMARY OF THE INVENTION

Against this background, it is the object of the present invention to provide a bag in which material can be saved in the bottom area, while ensuring good protection of the filling contents and sufficient strength also in the bottom area.

According to the invention, the object is achieved by a bag with the features herein. Advantageous embodiments are the subject-matter of the description herein.

The bags according to the invention are formed from a single-layer or multilayer web-like material, in particular paper and/or other sheet-like material, and have at least one bottom formed in a cross bottom or block bottom folding manner. The corner turn-ins of the bottom fold are located at the two ends of the longitudinal bottom axis, and the side flaps of the bottom fold run essentially parallel to the longitudinal bottom axis and are folded closed around the side fold lines of the bottom fold when the bottom is laid closed. The folded side flaps have an overlap. According to the invention, the width of the overlap is a maximum of 10 millimeters, preferably a maximum of 6 millimeters and further preferably a maximum of 4 millimeters.

With these overlap widths, the width of the overlap is reduced significantly below the dimension usually required for mutual gluing of the side flaps on common bag making machines. By reducing the width of the overlap compared to previously known bags, a significant material saving is achieved, which also increases the environmental friendliness of the bags, especially if they comprise layers of material made of plastic or other less environmentally friendly materials. The length of the piece of tubing from which the bag is made can be significantly reduced for the same filling volume of the bag compared to previously known bags with glued overlap. At the same time, the presence of a narrow overlap continues to ensure adequate protection of the filling contents because a gap between the closed side flaps is avoided. Preferably, the side flaps are not glued together in the area of their overlap. The bottom fold can be fixed in any other way than by gluing the overlap of the side flaps, e.g. by gluing on a cover sheet.

Advantageously, it is provided that the overlap of the side flaps is at least 1 millimeter, preferably at least 2 millimeters, further preferably at least 4 millimeters and further preferably at least 6 millimeters. The minimum width of the overlap is better in terms of ensuring good protection of the filling contents and good strength of the bag bottom.

In a preferred embodiment, a bottom of the bag is designed as a valve bottom into which a valve for filling the bag is incorporated. Advantageously, the valve is formed as a valve tube which is inserted in the region of a corner turn-in of the bottom fold. Particularly advantageously, the inner end of the valve tube extends essentially only as far as the inner edge of the corner turn-in or as far as just before the inner edge of the corner turn-in. Due to the reduced overlap of the side flaps or the reduced length of the piece of tubing from which the bag is formed, the corner turn-ins also require less material. In particular, the corner turn-ins have a reduced width in the direction of the longitudinal axis of the bottom, i.e. the corner turn-ins extend less far from the ends of the longitudinal axis of the bottom towards the center of the bottom. In the case of valve bags, this width of the corner turn-ins typically has to be overcome by the valve tube so that the filling material can be introduced into the bag as smoothly as possible. In the case of the bags according to the invention, the less wide corner turn-ins mean that the distance to be covered by the valve hose is shorter, so that valve material can be saved. The valve hose is often formed from comparatively expensive material, e.g. a thermal material, in order to be able to weld the valve after filling the bag. The shortening of the valve hose according to the invention is therefore associated with significant material and cost savings. Accordingly, the bottom design according to the invention is particularly advantageous for a valve bottom. Advantageously, the shortening of the valve hose is designed in such a way that the inner end of the valve hose is shortened relative to the inner edge of the corner turn-ins, this shortening preferably being 3 mm, further preferably 6 mm and still further preferably 1 cm.

A valve can be inserted as a prefabricated, closed valve tube into the still open bottom fold. Alternatively, it is also possible to insert a so-called valve patch into the still open bottom fold to form the valve, so that the valve patch is formed into a tube by adding the side flaps. In this embodiment, material savings are also possible because the valve patch can be made less wide transverse to the bottom longitudinal axis.

In an advantageous embodiment, the bag has two opposite bottoms, which are configured according to the invention. The side wall of the bag extends between these two bottoms. Due to the design of both bottoms according to the invention with a small overlap of the side flaps, a material saving can be achieved for both bottoms according to the invention. Particularly advantageously, one of the two bottoms is designed as a valve bottom, and the other as a stand bottom.

In another preferred embodiment, the bag is an open cross or block bottom bag that is filled through an opening opposite the bottom.

The bag according to the invention can be designed as a single-layer bag. In a preferred embodiment, the bag is designed as a multilayer bag, the material layers preferably consisting of paper and / or coated paper and/or plastic. In the case of multi-layer bags, the material savings in bottom formation have a particularly advantageous effect.

In a further preferred embodiment, the bag is made of three layers, the innermost and the outermost material layer being made of paper or coated paper, and the intermediate material layer being made of plastic. In this way, particularly good product protection can be achieved in the area of the entire bag, including the bottom area, while at the same time ensuring great strength of the bag.

Advantageously, the bag is formed of compostable and/or recyclable materials, in particular paper and / or coated paper.

In another preferred embodiment, at least one of the bottoms is provided with an inner tack and/or a cover sheet. An inner tack is glued into the still open bottom fold in a known manner. A cover sheet is used to glue over the closed side flaps of the bottom fold. The inner tack and/or the cover sheet can be used to increase the protection of the filling contents in the bottom area and/or to fix the bottom fold. In the case of bags with two bottoms, the inner tack and/or cover sheet can be present on one or both bottoms. In the case of bases with an inner latch, an opening aid, preferably a tear strip, can also be provided in one base, preferably in the standing base.

In a preferred embodiment, the inner latch and/or the cover sheet can consist of paper, in particular simple and/or less resistant paper, since the overlapping of the side flaps ensures good protection of the filling contents. In another preferred embodiment, the inner latch and / or the cover sheet consists of a PE-coated paper and / or a film. This provides even better protection for the filling contents.

Another advantageous embodiment is the omission of an inner latch and the application of a cover sheet over substantially the entire bottom, which allows the bottom fold to be well fixed and the filling contents to be well protected.

In another preferred embodiment, the piece of tubing from which the bag is formed has a smooth cut at at least one, preferably at both ends, in which the cut line perpendicular to the direction of the tubing has a continuous course at the ends of the piece of tubing. Such a smooth cut permits, in a simple manner from the point of view of production technology, that in addition to the side flaps a corresponding saving of material is also achieved in the corner turn-ins of the bottom fold.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of embodiments of the invention are explained in more detail with reference to the figures below. Thereby show:

FIG. 1: A bag with unfolded cross bottom according to the prior art.

FIG. 2: The open cross bottom of a bag according to the invention.

FIG. 3: The open cross bottom of a bag according to the invention with inner latch

FIG. 4: The feeding of the cross bottom of a bag according to the invention

FIG. 5: The closing of a cross bottom of a bag according to the invention

FIG. 6: The closed cross bottom, glued over with a cover sheet

FIG. 7: The open cross bottom of a bag according to the invention with valve

FIG. 7a : The open cross-bottom of a bag according to the invention with a valve tube extending to the inner edge of the corner turn-in.

FIG. 7b : The open cross bottom of a bag according to the invention with a valve tube that does not extend to the inner edge of the corner turn-in.

FIG. 8: The open cross bottom of a bag according to the invention with inserted valve patch.

FIG. 8a : The open cross-bottom of a bag according to the invention with inserted valve patch, which extends to the inner edge of the corner turn-in.

FIG. 8b : The open cross bottom of a bag according to the invention with inserted valve patch, which does not extend to the inner edge of the corner turn-in.

FIG. 9: A paper web section for the production of a bag according to the invention.

Description of the Preferred Embodiments

FIG. 1 shows a bag 1 with an unfolded cross bottom 3 according to the prior art. To close the bottom, first the front side flap 8 is folded in and then the rear side flap 7 is folded onto it, and in their overlap area the two side flaps are glued with the adhesive strip 9. Common bag making machines require a comparatively wide overlap in order to be able to apply an adhesive strip in a practicable manner.

FIG. 2 shows a bag 10 according to the invention with an open cross bottom 20. The bottom 20 is divided into two halves by the longitudinal bottom axis 21. Characteristic of the cross bottom fold are the corner turn-ins 22 and 23 as well as the side flaps 25 and 26, which are folded closed around the side fold lines 28 and 29 for closing the bottom 20. Extending downward from the bottom 20 is the sidewall 16 of the bag.

In FIG. 3, an inner tack 40 is inserted into the open cross bottom 20. The inner tack 40 covers the inner edges of the folded-in corner turn-ins 22 and 23 and extends from the bottom longitudinal axis 21 to above the side fold lines 28 and 29. Advantageously, the inner tack is glued to the inner edges of the corner flaps and the side flaps with a frame glueing. This provides good protection for the filling contents.

FIG. 4 shows the closing of the side flaps 25 and 26 of the cross bottom 20 of a bag 10 according to the invention. An inner bolt 40 is inserted into the bottom 20. First, the front side flap 26 is folded shut and then the rear side flap 25 is folded onto it.

FIG. 5 shows the closed cross bottom 20 of a bag 10 according to the invention. In the closed state, the side flaps 25 and 26 overlap only to a small extent. The width of the overlap of the side flaps results from the distance between the edge 35 of the rear side flap 25 and the edge 36 of the front side flap 26. Since the front side flap 26 is folded in first, its edge 36 is covered by the rear side flap 25 folded in afterwards. Therefore, the edge 36 of the front side flap 26 is shown as a dashed line, and the unconcealed edge 35 of the rear side flap 25 is shown as a solid line. According to the invention, the distance between the edges 35 and 36 or the width of the overlap of the side flaps 25 and 26 is at most 10 millimeters. Preferably, the overlap is a maximum of 4 millimeters and further advantageously a maximum of 2 millimeters.

Due to the smaller side flap overlap, the bag can be formed in an overall more material-saving way. Due to the small width of the overlap, an adhesive strip cannot be suitably applied with the machines commonly used in bag production. It is therefore provided in accordance with the invention to fix the bottom fold in a way other than by mutual gluing of the side flaps in the overlap area. For example, the bottom fold can be fixed by gluing-on a cover sheet. This is illustrated in FIG. 6. There, the added cross bottom 20 has a cover sheet 45 glued over it, which fixes the bottom fold.

FIG. 7 shows a variant of a bag 10 according to the invention with a still open cross bottom 20 into which a valve 50 in the form of a prefabricated valve tube is inserted. As a result of the narrower design of the side flaps 25 and 26, the corner turn-ins 22 and 23 are also narrower in the longitudinal direction of the bottom. As a result, the valve tube 50 also only has to travel a shorter distance in order to insert the filling material into the bag without any problems. In this way, the valve 50 can also be manufactured in a more material-saving manner. FIG. 7a shows a variant in which the valve hose 50 extends as far as the inner edge 24 of the corner turn-in 22. This means that slightly more valve material can be saved in this variant than in the variant shown in FIG. 7, in which the valve hose protrudes beyond the inner edge 24 of the corner turn-ins 22. FIG. 7b shows a variant in which the valve hose 50 is shortened at its inner end 54 relative to the inner edge 24 of the corner turn-ins 22. Preferably this shortening is 3 mm, further preferably 6 mm and still further preferably 1 cm. Even more valve material can be saved by the design according to FIG. 7b .

FIG. 8 shows a variant of the bag 10 according to the invention with the cross bottom 20 still open, into which a valve patch 52 is inserted to form a valve. When the side flaps 25 and 26 are closed, the valve patch 52 is formed into a valve tube. In the variant shown in FIG. 8, the inner edge 56 of the valve patch extends slightly further to the center of the material base than the inner edge of the corner turn-in 22. FIG. 8a shows a variant with a valve patch 52 in which the inner edge 56 of the valve patch extends to the inner edge 24 of the corner turn-in 22, so that the valve patch 52 and the corner turn-in 22 are flush with each other at the edges 24 and 56. FIG. 8b shows a variant in which the valve patch 52 does not extend with its inner edge 56 as far as the inner edge 24 of the corner turn-ins 22, so that the valve tube 52 is shortened at its inner end 54 relative to the inner edge 24 of the corner turn-ins 22. Particularly advantageously, the shortening is 3 mm, further advantageously 6 mm and even further advantageously 1 cm. As a result, even more valve material can be saved in this embodiment.

FIG. 9 shows a paper web section 12 for producing a bag according to the invention on a continuous paper roll 11. The fold lines of the cross bottom fold are indicated in dashed lines. The rectangular panels 16 form the sidewall 16 of the bag. Along the cut lines 13 and 14, the paper web sections 12 are cut to form individual tube pieces. Accordingly, the cut lines 13 and 14 represent the cut lines of the tube pieces perpendicular to the tube direction. FIG. 7 shows cut lines 13 and 14 formed with a smooth cut, which run continuously perpendicular to the tube direction. With a reduced tube length, a smooth cut can save material both in the area of the side flaps and in the area of the corner turn-ins. 

1. Bag (10) for bulk material of paper and/or other sheet material, with at least one bottom formed in a cross or block bottom folding manner, wherein the bottom folding comprises two side flaps (25, 26) which are folded about side fold lines (28, 29) extending in the longitudinal direction of the bottom for bottom formation, wherein the side flaps form an overlap in the closed state, and the width of the overlap is at most 10 millimeters, preferably at most 6 millimeters and further preferably at most 4 millimeters.
 2. Bag according to claim 1, wherein the width of the overlap is at least 1 millimeter, preferably at least 2 millimeters and further preferably at least 4 millimeters.
 3. Bag according to claim 1 ,wherein the bottom is formed as a valve bottom in which a valve (50) for filling the bag is incorporated.
 4. Bag according to claim 1, wherein the valve (50, 52) is inserted in the region of a corner turn-in (22, 23) of the bottom fold, the inner end of the valve (54, 56) extending substantially to the inner edge (24) of the corner turn-in.
 5. Bag according to claim 3, wherein the valve (50, 52) is inserted in the region of a corner turn-in (22, 23) of the bottom fold, the inner end (54, 56) of the valve (50, 52) being shortened relative to the inner edge (24) of the corner turn-in (22), the shortening being preferably 3 mm, further preferably 6 mm and still further preferably 1 cm.
 6. Bag according to claim 1 wherein the valve (50) is formed as a valve tube (50) and/or as a valve patch (52).
 7. Bag according to claim 1, comprising two opposite bottoms between which a side wall (16) of the bag extends.
 8. Bag according to claim 1, wherein the bag is designed as an open cross-bottom or block-bottom bag.
 9. Bag according to claim 1 ,wherein the bag is designed as a multilayer bag, the material layers preferably selected from the group consisting of paper, coated paper, plastic, and mixtures thereof.
 10. Bag according to claim 9, wherein the bag is formed of three layers, the innermost and the outermost material layer being formed of paper and intermediate material layer being formed of plastic film.
 11. Bag according to claim 1, wherein the bag is formed of compostable and/or recyclable materials, in particular paper and/or coated paper.
 12. Bag according to claim 1, wherein at least one of the bottoms is provided with an inner latch (40) and/or a cover sheet (45).
 13. Bag according to claim 1, wherein the inner latch comprises uncoated paper, PE-coated paper and/or film.
 14. Bag according to claim 1, wherein wherein the bag is formed from a piece of tubing which has a smooth cut at least one, preferably both ends (13, 14).
 15. Bag according to claim 2, wherein the bottom is formed as a valve bottom in which a valve (50) for filling the bag is incorporated.
 16. Bag according to claim 15, wherein the valve (50, 52) is inserted in the region of a corner turn-in (22, 23) of the bottom fold, the inner end of the valve (54, 56) extending substantially to the inner edge (24) of the corner turn-in.
 17. Bag according to claim 15, wherein the valve (50, 52) is inserted in the region of a corner turn-in (22, 23) of the bottom fold, the inner end (54, 56) of the valve (50, 52) being shortened relative to the inner edge (24) of the corner turn-in (22), the shortening being preferably 3 mm, further preferably 6 mm and still further preferably 1 cm.
 18. Bag according to claim 17, wherein the valve (50) is formed as a valve tube (50) and/or as a valve patch (52).
 19. Bag according to claim 16, wherein the valve (50) is formed as a valve tube (50) and/or as a valve patch (52).
 20. Bag according to claim 15, wherein the valve (50) is formed as a valve tube (50) and/or as a valve patch (52). 